A variety of isotactic crystallizable polymers of vinyl aromatic polymers such as styrene and certain substituted styrenes are known. Sterospecific polymerization with Ziegler catalysts, for example, has been used successfully to prepare isotactic crystallizable polymers from styrene and many members of the styrene family as described in Natta et al, Makromol. Chemie 28,253 (1958) reprinted in Natta and Danusso, "Stereoregular Polymers, and Stereospecific Polymerizations", Pergammon Press Ltd., London, 1967, Volume 2, p. 570. However, Natta et al report that p-fluourostyrene is the only mono-para-substituted styrene they were able to polymerize to a crystalline isotactic polymer. In contrast they found the ortho- and meta-isomers readily gave methylstyrene polymers which were crystallizable. Nor have we found crystalline isotactic poly(para-methylstyrene) reported elsewhere in the literature.